The present invention relates to method and apparatus specimen fabrication for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer or a device or preparing the micro sample to be separated by using a focused ion beam.
Electronic parts such as a semiconductor memory typified by a dynamic random access memory, a microprocessor, a semiconductor device such as a semiconductor laser, and a magnetic head are required to be manufactured in a high yield since decrease in the manufacturing yield due to occurrence of a defect causes profit deterioration. Consequently, early detection/measure of/against a defect, a foreign matter, and poor processing as causes of a failure are big tasks. For example, at a site of manufacturing a semiconductor device, energies are put into finding a failure by a careful test and analyzing the cause of the failure. In an actual electronic part manufacturing process using a wafer, a wafer being processed is tested, the cause of an abnormal portion such as a defect in a circuit pattern or a foreign matter is tracked down, and a measurement to be taken is examined.
Usually, to observe a fine structure of a sample, a scanning electron microscope (hereinbelow, abbreviated as SEM) with high resolution is used. However, as the packing density of a semiconductor device is becoming higher, an object cannot be observed with the resolution of the SEM. Therefore, in place of the SEM, a transmission electron microscope (hereinbelow, abbreviated as TEM) having higher observation resolution is used.
Conventional TEM sample fabrication is accompanied by a work of making a sample into small pieces by cleaving, cutting, or the like. When the sample is a wafer, in most cases, the wafer has to be cut.
Recently, there is a micro area processing method of irradiating a sample with an ion beam and applying an action that particles constructing the sample are released from the sample by sputtering, that is, a method of using a process with a focused ion beam (hereinbelow, abbreviated as FIB). According to the method, first, a strip pellet having a thickness of sub millimeters including an area to be observed is cut from a sample such as a wafer by using a dicer or the like. A part of the strip pellet is processed with an FIB into a thin film state to thereby prepare a TEM sample. The feature of the sample for TEM observation processed with the FIB is that a part of a specimen is processed to a thin film having a thickness of about 100 nm for the TEM observation. Although the method enables a requested observation area to be positioned with accuracy of a micrometer level and to be observed, still, the wafer has to be cut.
Although monitoring a result of a process during fabrication of a semiconductor device or the like has an big advantage from the viewpoint of managing the yield, a wafer is cut for preparation of a sample as described above and a piece of the wafer is not subjected to a following process but is discarded. In recent years, particularly, the diameter of a wafer is increasing to reduce the price of manufacturing a semiconductor device. Specifically, the number of semiconductor devices which can be manufactured from a single wafer is increased to reduce a unit price. However, it increases the price of the wafer itself, an added value increases as the manufacturing process advances and, further, the number of semiconductor devices lost by discarding a wafer increases. Therefore, the conventional test method accompanying cutting of the wafer is very uneconomical.
To deal with the problem, there is a method of preparing a sample without cutting a wafer. The method is disclosed in Japanese Patent Application No. H05-52721, xe2x80x9cMethod of separating sample and method of analyzing sample separated by the separating methodxe2x80x9d (known technique 1). According to the method, as shown in FIGS. 2(a) to 2(g), first, the posture of a sample 2 is maintained so that the surface of the sample 2 is irradiated with an FIB 1 at the right angle and scanned with the FIB 1 in a rectangular shape, and a rectangular hole 7 having a required depth is formed in the surface of the sample (FIG. 2(a)). Subsequently, the sample 2 is tilted and a bottom hole 8 is formed. The tilt angle of the sample 2 is changed by a specimen stage (not shown) (FIG. 2(b)). The posture of the sample 2 is changed, the sample 2 is disposed so that the surface of the sample 2 becomes perpendicular to the FIB 1 again, and a trench 9 is formed (FIG. 2(c)). By driving a manipulator (not shown), the tip of a probe 3 at the end of the manipulator is made come into contact with a portion to be separated in the sample 2 (FIG. 2(d)). A deposition gas 5 is supplied from a gas nozzle 10, and an area including the tip of the probe 3 is locally irradiated with the FIB 1 to form an ion beam assist deposition film (hereinbelow, simply called deposition film 4). The separation portion in the sample 2 and the tip of the probe 3 which are in contact with each other are connected to each other by the deposition film 4 (FIG. 2(e)). The peripheral portion is trenched with the FIB 1 (FIG. 2(f)), and a micro sample 6 as a sample separated from the sample 2 is cut. The cut separated sample 6 is supported by the connected probe 3 (FIG. 2(g)). The micro sample 6 is processed with the FIB 1 and the area to be observed is walled, thereby obtaining a TEM sample (not shown). According to the method, a micro sample including a requested analysis area is separated from a sample such as a wafer by using a process with an FIB and means for carrying the micro sample. The micro sample separated by the method is introduced to any of various analyzers and can be analyzed.
A similar sample fabricating method is disclosed in Japanese Patent Application Laid-Open No. H09-196213, xe2x80x9cApparatus and method for preparing micro samplexe2x80x9d (known technique 2). According to the method, as shown in FIGS. 9(a) to 9(j), first, the FIB 1 is emitted to form marks 403 and 404 for identifying a target position and, after that, rectangular holes 401 and 402 are formed on both outer sides of the marks 403 and 404 in the sample 2 (FIG. 9(a)). Subsequently, a trench 406 is formed with the FIB 1 (FIG. 9(b)). The specimen stage is tilted and the surface of the sample is obliquely irradiated with the FIB 1, thereby forming a tapered trench 408, and an extraction sample 407 which is connected to the sample 4 only via a residual area 405 is formed (FIG. 9(c)). The tilted specimen stage is returned to the original position and the probe 3 is controlled by a probe controller so as to come into contact with a part of the extraction sample 407. The residual area 405 of the extraction sample 407 will be cut with an FIB later. In consideration of a probe drift or the like, it is desirable to cut the residual area 405 in short time, so that the volume of the residual area 405 has to be low. Consequently, due to a fear that the residual area 405 is destroyed by the contact of the probe 3, the probe 3 is made contact while preventing a damage as much as possible by using the probe controlling method. The probe 3 and the extraction sample 407 which are in contact with each other are fixed by using a deposition film 409 (FIG. 9(d)). Subsequently, the residual area 405 is cut with the FIB 1 (FIG. 9(e)). In such a manner, the extraction sample 407 is cut out, and the probe 3 is lifted by the probe driving apparatus to extract the extraction sample 407 (FIG. 9(f)). Subsequently, the cut extraction sample 407 is allowed to come into contact with a trench 411 formed in an extracted sample holder (FIG. 9(g)). At this time, the extraction sample 407 has to come into contact at a sufficiently low speed so that the extraction sample 407 is not destroyed or is not come off from the connected portion with the deposition film 409, so that the contacting method is necessary. After making the extraction sample 407 contact with the trench 411, they are fixed by using a deposition film 412 (FIG. 9(h)). After the fixing, the probe 3 connection portion is irradiated with the FIB, and sputtering is performed to separate the probe from the extraction sample 407 (FIG. 9(i)). In the case of preparing a TEM sample, finally, the FIB 1 is emitted again to finish an observation area 410 so that the thickness of the observation area 410 becomes about 100 nm or less (FIG. 9(j)). In the case of preparing a sample for analysis or measurement, the finishing process for making the observation area thin (FIG. 9(j)) is not always necessary.
The example of employing the method of extracting a micro sample by the sample fabricating apparatus has been described above. There is also a method of processing the shape of a micro sample by the sample fabricating apparatus, taking out the base from the sample fabricating apparatus, and extracting the micro sample by another mechanism in atmosphere. For example, such a method is described by L. A. Giannuzzi et al., xe2x80x9cFocused Ion Beam Milling and Micromanipulation Lift-Out for Site Specific Cross-Section TEM Specimen Preparationxe2x80x9d, Material Research Society, Symposium Proceeding Vol. 480, pp. 19 to 27 (known technique 3). Similarly, it is also described by L. R. Herlinger, xe2x80x9cTEM Sample Preparation Using a Focused Ion Beam and a Probe Manipulatorxe2x80x9d, Proceedings of the 22nd International Symposium for Testing and Failure Analysis, pp. 199 to 205 (known technique 4).
According to such a method, as shown in FIG. 3(a), both sides of a target position on a wafer 208 are processed in a stair shape with the FIB 1 to form a sample membrane 207, a specimen stage is tilted to change the angle formed between the FIB 1 and the surface of the sample, and the sample is irradiated with the FIB 1. As shown in FIG. 3(b), the periphery of the sample membrane 207 is cut with the FIB 1, thereby separating the sample membrane 207 from the wafer. The wafer is taken out from an FIB system, a glass stick is allowed to approach the process portion in the atmosphere, the sample membrane 207 is attracted by the glass stick by using static electricity and is separated from the wafer, the glass stick is moved above a mesh 209 and is attracted by the mesh 209 by using static electricity or disposed so that the process face faces a transparent attachment. As described above, the processed micro sample in the system may not be taken out in the system. Even when most of the outer shape of the micro sample is processed with an ion beam, the separated micro sample is introduced into the TEM, and can be analyzed.
By using any of the methods, without cutting a wafer, only a micro sample or a membrane sample for test is extracted from a sample, and the wafer from which the sample is extracted can be returned to the next process. Therefore, unlike the conventional techniques, there is no semiconductor device which is lost by the cutting of a wafer, the manufacturing yield of the semiconductor device is increased in total, and the manufacturing cost can be reduced.
In the case of forming a hole by using sputtering of irradiating the surface of a sample with an ion beam and observing a section of the hole by an FIB system or a scanning electron microscope (SEM), the section is formed at an end of an ion beam scan range.
However, the actually formed section is not perfectly perpendicular to the surface of a sample due to flare of a processing beam and re-deposition of a sputtered substance, and a slight taper exists. An FIB system having a mechanism of tilting a specimen stage can prevent the taper by tilting a sample by an angle corresponding to the taper, for example, about 0.5 degree and irradiating the tilted sample with an ion beam and form an observation section having higher perpendicularity. The method is described as, for example, processing of a sample section of a transmission electron microscope (TEM), in xe2x80x9cElectron and ion beam handbook, Third Editionxe2x80x9d, Japan Society for the Promotion of Science, 132 commission, Nikkan Kogyo Shinbun Sha, pp. 459 and 460 (known technique 5).
The conventional methods have the following problems. Specifically, to form the bottom hole 8 in the first known technique, to form the tapered trench 408 in the second known technique, and to cut the periphery of the sample membrane 207 in the fourth known technique, the posture or tilt angle of the sample 2 is changed as a necessary process by the specimen stage. However, as the diameter of a wafer increases, the specimen stage also becomes larger. Consequently, a problem such that it takes time to tile a large stage with high accuracy and, as a result, sample fabrication time becomes longer arises. Due to heavy weight of the specimen stage itself, the eucentric is not maintained before and after the tilting and the sample position relative to the ion beam irradiating optical system moves, so that the focal point of the FIB is relatively largely deviated from the surface of the sample, the surface of the sample cannot be observed, and a problem such that the ion beam irradiating optical system has to be re-adjusted also occurs. The function of tilting the specimen stage causes increase in the size of the specimen stage itself and in the size of a specimen chamber for housing the specimen stage. The trend of the diameter of a wafer is shifting from 200 mm to 300 mm. When the diameter of a wafer is further increased to 400 mm, the size of the stage has to be increased and the problem which occurs in association with the tilt of the specimen stage has to be solved. In contrast, when the function of tilting the specimen stage of the system can be eliminated, miniaturization of the whole system can be realized and a problem such as a deviation of the sample position accompanying a tilt of the sample is solved. However, by the above-described conventional methods, fabrication of a sample for analyzing, observing or measuring a micro area by separating a micro sample from an original sample (wafer) or preparing the micro sample to be separated cannot be realized. Originally, the change in the tilt angle or posture of a sample is required due to existence of the fixed idea that the surface of a sample has to be irradiated with ion beams in at least two directions at different angles to separate a micro sample from an original sample or prepare the micro sample to be separated. The tilting of the stage denotes here turning of a stage around a line segment included in or parallel to the stage plane as an axis. It will be simply described as tilting of a stage herein later.
By an FIB controller in which a specimen stage has the tilting function, an FIB can be emitted at an arbitrary angle, and can eliminate the taper as in the known technique 5.
On the other hand, the function of tilting a specimen stage can be omitted from the system, the miniaturization of the whole system is realized, and the program such as a deviation of the sample position which occurs in association with the tilting of a sample can be solved. However, according to the conventional methods, it is difficult to emit an FIB at an arbitrary angle. A method of obliquely irradiating the surface of a sample with an ion beam to form a hole, thereby enabling an observation section to be formed is disclosed as xe2x80x9cSection observing methodxe2x80x9d in Japanese Patent Application Laid-Open No. H03-166744 (known technique 6). Although a process of forming a vertical section by the method is described, a method of optionally changing an irradiation angle without tilting a specimen stage is not mentioned. Consequently, it is difficult to eliminate the taper.
In consideration of the problems, a first object of the invention is to provide a sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from an original sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting a specimen stage by breaking down the conventional fixed idea. A second object is to provide a sample fabricating apparatus suitable for achieving the first object. A third object is to realize a sample fabricating apparatus and a sample fabricating method which can form a section by irradiation with an FIB at an arbitrary angle in a certain range even when a not-tilting specimen stage is used.
Terms used in the specification will be defined as follows.
A requested section is a section the operator of the apparatus intends to prepare. A set section denotes a section obtained when it is assumed that a set ion beam scanning area is ideally processed without an influence of a beam diameter, re-deposition, or the like. A formed section is a section actually formed with an FIB. A formed-section edge is a cross line between the formed section and the surface of a sample. A set-section edge is a cross line between the set section and the surface of a sample. A scanning-area edge is one of the sides of an ion bean scanning area. A requested-section edge is a cross line of a requested section and the surface of a sample. A requested-section edge normal direction is a direction of a normal line in a sample surface of a requested section edge, which extends from the sample to a process space. A requested section normal direction is a direction of a normal line of a requested section, which extends from the inside of the sample to a process space. A requested depression angle is an angle formed between the requested-section normal direction and the sample surface. The requested depression angle is positive in the case where the requested-section normal line direction extends from the sample surface to the inside of the sample, and is negative in the case where the requested-section normal line direction extends from the inside of the sample to the surface of the sample (corresponding to an elevation angle). A set-section depression angle is an angle formed between the set-section normal line direction and the sample surface. The set-section depression angle is positive when the set-section normal line direction extends from the sample surface to the inside of the sample and is negative when the set-section normal line direction extends from the inside of the sample to the surface of the sample (corresponding to an elevation angle).
The first object of the invention is achieved as follows.
Basic aspects of the invention to break down the conventional fixed idea that the tilt angle or the posture of a sample has to be changed are as follows.
(1) An ion beam processing method for separating a requested portion in a sample or preparing the requested portion by irradiating the sample with an ion beam from a plurality of directions while fixing an angle formed between a sample placement face and an optical axis of an ion beam to the sample.
According to the invention, the ion beam processing method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized.
(2) A sample separating method for irradiating a sample with an ion beam while setting an angle formed between the optical axis of the ion beam emitted to the sample and the surface of the sample to be larger than 0 degree and smaller than 90 degrees and irradiating a requested portion in the sample with the ion beam while fixing an angle formed between the optical axis of the ion beam emitted to the sample and the sample surface to thereby separate the requested portion or prepare the requested portion to be separated.
According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized.
(3) A sample separating method for irradiating a sample with an ion beam while setting an angle formed between the optical axis of the ion beam emitted to the sample and the sample surface to be a range from 30 degrees to 75 degrees, and irradiating a requested portion in the sample with the ion beam while fixing the angle formed between the optical axis of the ion beam emitted to the sample and the sample surface, thereby separating the requested portion or preparing the requested portion to be separated.
According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized. Particularly, by setting the FIB irradiation angle in the range from 30 degrees to 75 degrees, the surface of the sample can be observed excellently, and the shape of the micro sample is formed to be suitable for fabrication.
(4) The object is also realized by a sample fabricating method for separating a micro sample from a sample or preparing the micro sample to be separated by using a sample fabricating apparatus including at least a focused ion beam irradiating optical system, secondary particle detecting means for detecting secondary particles generated from a sample irradiated with the focused ion beam, and a specimen stage on which a specimen base is placed, in which the sample is irradiated with the focused ion beam by setting the angle formed between the optical axis of the focused ion beam emitted to the sample and the sample surface to be larger than 0 degree and smaller than 90 degrees, and the sample is turned by using a sample surface normal line as a turning axis and is irradiated with the ion beam while fixing the angle formed between the optical axis of the focused ion beam to the sample and the sample surface.
That is, an aspect of the invention for breaking down the conventional fixed idea is to include an operation of turning a specimen stage around the line normal to the sample surface as a turning axis into the sample fabricating method in accordance with an object. According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized.
Also in the case of an apparatus in which the specimen stage has the tilting function, the time required to tilt the stage is unnecessary so that the sample fabricating time is made relatively short. The problem such that the sample surface cannot be observed before and after the specimen stage is tilted is also reduced.
(5) In the sample fabrication method of (4), the requested portion in the sample is supported by a probe.
According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized. By supporting the micro sample by the probe and extracting the micro sample from the specimen base, the section of the micro sample can be observed in detail, and the position of processing the section can be controlled with high precision. As the method of supporting the micro sample, any method can be used as long as the micro sample can be supported such as fixing by using a deposition film, fixing by using static electricity, or the like.
(6) A sample fabricating method for observation, analysis, or measurement, including: a step of forming a sample connected to a specimen base via a residual area by a step of forming a rectangle hole by irradiating the sample with a focused ion beam while setting an angle formed between the optical axis of the focused ion beam emitted to the sample and the sample surface to be larger than 0 degree and smaller than 90 degrees, a step of turning the sample by using a sample surface normal line as a turning axis, and a step of forming a tapered trench in the surface of the specimen base by emitting a focused ion beam after the turn; a step of fixing the connected sample to a requested portion of transfer means by making a requested portion in the connected sample contact with the requested portion of the transfer means, and forming a deposition film in an area including the contact portion by irradiating the area with a focused ion beam while supplying a deposition gas; and a step of cutting the residual area by emitting a focused ion beam.
According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized. The section of the micro sample can be observed in detail, and the section process position can be controlled with high precision.
(7) A sample fabricating method for observation, analysis, or measurement, including: a step of forming a membrane by forming a rectangle hole by emitting a focused ion beam while setting an angle formed between the optical axis of the focused ion beam emitted to the sample and the sample surface to be larger than 0 degree and smaller than 90 degrees; a step of turning the sample by using a sample surface normal line as a turning axis, and a step of separating the sample membrane or preparing the sample membrane to be separated by emitting a focused ion beam after the turn.
According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized. Since a process of forming an ion beam assist deposition film or the like is not included, the sample fabrication time can be shortened.
(8) In the sample fabricating method in any of (3), (4), (5), (6), and (7), in order to separate at least two micro samples or prepare the micro samples to be separated, the peripheral area of each of micro samples is processed to some midpoint of all the processes, the sample is turned, and the process of the peripheral area of each of the micro samples is sequentially continued.
According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized. Particularly, a plurality of samples can be prepared with high throughput.
The second object of the invention is achieved as follows.
(9) A sample fabricating apparatus including at least a focused ion beam irradiating optical system and a specimen stage on which a specimen base is placed, for separating a micro sample from the specimen base or preparing the micro sample to be separated, wherein an angle formed between an almost center axis of a mechanical column including the focused ion beam irradiating optical system and the sample placement face of the specimen stage is fixed, and the apparatus has a separator for separating a desired portion in the sample and a probe for supporting the separated sample.
According to the invention, the sample fabricating method for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample without tilting a specimen stage can be realized. By supporting the micro sample by the probe and extracting the micro sample from the specimen base, the section of the micro sample can be observed in detail, and the sample fabricating apparatus capable of controlling the section process position with high precision can be realized. As the method of supporting the micro sample, any method can be used as long as the micro sample can be supported such as fixing by using a deposition film, fixing by using static electricity, or the like.
(10) A sample fabricating apparatus for separating a micro sample from a specimen base or preparing the micro sample to be separated, including at least a focused ion beam irradiating optical system, secondary particle detecting means for detecting secondary particles generated from a sample irradiated with the focused ion beam, and a specimen stage on which a specimen base is placed, wherein the angle formed between the optical axis of the focused ion beam emitted to the sample and the sample surface is larger than 0 degree and smaller than 90 degrees, the specimen stage has the function of turning around a sample surface normal line as a turn axis, and the apparatus has the function of determining, after the turn, the position irradiated with the focused ion beam for separating a sample or preparing the sample to be separated by using image displaying means for displaying a secondary particle image formed by secondary particles generated from the sample irradiated with the focused ion beam or an electron beam emitted from an electron beam emitting system separately provided.
According to the invention, the sample fabricating apparatus for preparing a sample for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting the specimen stage, which is suitable from the viewpoints that operations of the apparatus can be automated and the burden on the operator can be lessened and can prepare a sample in which a damage in the sample surface is little in a short time can be realized.
(11) A sample fabricating apparatus for separating a micro sample from a specimen base or preparing the micro sample to be separated, including at least a focused ion beam irradiating optical system, secondary particle detecting means for detecting secondary particles generated from a sample irradiated with the focused ion beam, and a specimen stage on which a specimen base is placed, wherein the angle formed between the optical axis of the focused ion beam emitted to the sample and the sample surface is larger than 0 degree and smaller than 90 degrees, the specimen stage has the function of turning around a sample surface normal line as a turn axis, and the apparatus has the function of determining, after the turn, the position irradiated with the focused ion beam for separating a sample or preparing the sample to be separated by using a result of performing an image process on a secondary particle image formed by secondary particles generated from the sample irradiated with the focused ion beam or an electron beam emitted from an electron beam emitting system separately provided.
According to the invention, the sample fabricating apparatus for preparing a sample for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting the specimen stage, which is suitable from the viewpoints that operations of the apparatus can be automated and the burden on the operator can be lessened and can prepare a sample in which a damage in the sample surface is little in a short time can be realized.
(12) A sample fabricating apparatus for separating a micro sample from a specimen base or preparing the micro sample to be separated, including at least a focused ion beam irradiating optical system, secondary particle detecting means for detecting secondary particles generated from a sample irradiated with the focused ion beam, and a specimen stage on which a specimen base is placed, wherein the angle formed between the focused ion beam irradiating optical system and the sample surface is in a range from 30 degrees to 75 degrees, the specimen stage has a turning function around a normal line to the sample surface as a rotation axis, and the apparatus includes a transfer means for transferring an extracted micro sample which is a desired portion separated from the specimen base to another member, and a holding means of a sample holder on which the extracted micro sample is placed.
The sample fabricating apparatus is suitable for fabricating a sample for analyzing, observing, and measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting the specimen stage. Particularly, by irradiating the focused ion beam at an angle from 30 degrees to 75 degrees, the surface of the sample can be observed excellently, and the shape of the micro sample is suitable for easy fabrication. The sample fabricating apparatus capable of fabricating a sample in shorter time can be realized.
(13) A sample fabricating apparatus for separating a micro sample from a specimen base or preparing the micro sample to be separated, including at least a focused ion beam irradiating optical system, secondary particle detecting means for detecting secondary particles generated from a sample irradiated with the focused ion beam, and a specimen stage on which a specimen base is placed, in which the angle formed between the optical axis of the focused ion beam emitted to the sample and the sample surface is 45 degrees, the specimen stage has a function of turning around a sample surface normal line as a rotation axis, and the apparatus includes a transfer means for transferring an extracted micro sample which is a requested portion separated from the specimen base to another member, and a holding means of a sample holder on which the extracted micro sample is placed.
According to the invention, the sample fabricating apparatus for preparing a sample for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or by preparing the micro sample to be separated without tilting the specimen stage can be realized. The apparatus is suitable for separating a sample or preparing the sample to be separated since the angle of the focused ion beam can be set to 45 degrees in both of the cases of observing the sample surface and a section of the sample by irradiation with the focused ion beam under the same conditions. Further, the sample fabricating apparatus capable of preparing a sample having little damage in its surface in a short time can be realized.
(14) In the sample fabricating apparatus in any of (10), (11) (12), and (13), the optical axis of the focused ion beam emitted to the sample almost coincides with the mechanical center axis of an objective lens almost symmetrical with respect to the center as a component of the focused ion beam irradiating optical system.
According to the invention, the sample fabricating apparatus capable of fabricating a sample for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting the specimen stage can be realized by mechanically specifying the angle formed between the objective lens almost symmetrical with respect to the center as a component of the focused ion beam irradiating optical system and the surface of the specimen stage, so that designing of the apparatus can be simplified.
(15) A sample fabricating apparatus including at least a focused ion beam irradiating optical system, secondary particle detecting means for detecting secondary particles generated from a sample irradiated with the focused ion beam, and a specimen stage on which a specimen base is placed, in order to separate a micro sample from the specimen base or preparing the micro sample to be separated, for irradiating a peripheral area of the micro sample in the specimen stage with the focused ion beam from a plurality of incident directions to thereby separate the micro sample or prepare the micro sample to be separated, in which the focused ion beam irradiating optical system is provided with a focused ion beam tilting function of changing the optical axis of the focused ion beam emitted to the sample by at least 15 degrees.
According to the invention, the sample fabricating apparatus capable of fabricating a sample for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting the specimen stage can be realized by the focused ion beam tilting function capable of changing the incident direction of the focused ion beam at least by 15 degrees. Particularly, the focused ion beam incident angle can be selected in preparation of a sample, so that various sample fabricating methods and various sample shapes can be realized.
(16) In the sample fabricating apparatus of (15), the focused ion beam tilting function capable of changing the optical axis of the focused ion beam emitted to the sample by at least 15 degrees is realized by a mechanism of varying the tilt angle with respect to the specimen stage of a mechanical column including the focused ion beam irradiating optical system.
According to the invention, the sample fabricating apparatus capable of fabricating a sample for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting the specimen stage can be realized by the mechanism of varying the tilt angle with respect to the specimen stage of the mechanical column including the focused ion beam irradiating optical system. Particularly, the focused ion beam incident angle can be selected in preparation of a sample, so that various sample fabricating methods and various sample shapes can be realized.
(17) In the sample fabricating apparatus of (15), the focused ion beam tilting function capable of changing the optical axis of the focused ion beam emitted tot he sample by at least 15 degrees is realized by an electric deflecting mechanism.
According to the invention, the sample fabricating apparatus capable of fabricating a sample for analyzing, observing, or measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated without tilting the specimen stage can be realized by the electric deflecting mechanism. Particularly, the mechanical apparatus configuration is simplified, the manufacturing cost can be reduced, and the focused ion beam incident angle can be selected in preparation of a sample, so that various sample fabricating methods and various sample shapes can be realized.
(18) In the sample fabricating apparatus in any of (10), (11) (12), (13), (14), (15), (16), and (17), the specimen stage has a fixed tilt angle using a line segment included in the stage plane or a line segment parallel to the stage plane as a tilt axis.
According to the invention, since the specimen stage does not have the tilting function, miniaturization of the whole apparatus can be realized, and the sample fabricating apparatus capable of fabricating a sample for analyzing, observing, and measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated can be realized.
(19) In the sample fabricating apparatus in any of (9), (10), (11), (12), (13), (14), (15), (16), and (17), the specimen stage is constructed by combining a stage which is turned at a specific fixed angle and a stage which can be turned at an arbitrary angle.
According to the invention, since the specimen stage does not have the tilting function, miniaturization of the whole apparatus can be realized, and the sample fabricating apparatus capable of fabricating a sample for analyzing, observing, and measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated can be realized. Particularly, the apparatus is suitable for saving the time necessary for positioning and increasing the throughput of sample preparation.
(20) In the sample fabricating apparatus in any of (9), (10) (11), (12), (13), (14), (15), (16), and (17), the specimen stage is constructed by combining a stage which is turned at a fixed angle that is at least one of 90 degrees and 180 degrees and a stage which can be turned at an arbitrary angle.
According to the invention, since the specimen stage does not have the tilting function, miniaturization of the whole apparatus can be realized, and the sample fabricating apparatus capable of fabricating a sample for analyzing, observing, and measuring a micro area by separating a micro sample including a requested specific area from a sample of an electronic part such as a semiconductor wafer, a semiconductor device, or the like or preparing the micro sample to be separated can be realized. Particularly, the apparatus is suitable for saving the time necessary for positioning and increasing the throughput of sample preparation.
The third object of the invention is achieved by the following.
(21) A sample fabricating apparatus for forming a sample section in a sample by ion beam processing, including an ion beam optical system constructed by an ion source, a lens for condensing ions emitted from the ion source, and a deflector, an ion beam optical system controller for controlling the ion beam optical system, a detector for detecting secondary particles generated from a sample irradiated with an ion beam, a specimen stage for holding the sample, and a specimen-stage position controller for controlling the position of the specimen stage, in which an angle formed between the optical axis of the ion beam emitted from the ion beam optical system and the sample surface is fixed and formation of a sample section is controlled in correspondence with a set-section depression angle. Thus, also in the apparatus in which the tilting of the specimen stage with respect to the ion beam optical system cannot be changed, a section at an arbitrary tilt angle can be formed.
(22) A sample fabricating apparatus for forming a sample section in a sample by ion beam processing, including an ion beam optical system constructed by an ion source, a lens for condensing ions emitted from the ion source, and a deflector, an ion beam optical system controller for controlling the ion beam optical system, a detector for detecting secondary particles generated from a sample irradiated with an ion beam, a specimen stage for holding the sample, and a specimen-stage position controller for controlling the position of the specimen stage, in which the ion beam optical system controller has a construction that an angle formed between the optical axis of the ion beam emitted from the ion beam optical system and the sample surface is larger than 0 degree and smaller than 90 degrees, and controls an ion beam scan by the deflector in correspondence with a set-section depression angle of a set section. Thus, the FIB irradiating angle at the time of processing a section can be arbitrarily set.
(23) In the sample fabricating apparatus in each of (21) and (22), the ion beam optical system controller controls the deflector on the basis of angle information that a requested depression angle is projected to a plane including, as a normal line, the optical axis of the ion beam in correspondence with a set-section depression angle of a set section. Thus, the ion beam processing set angle is controlled and the FIB irradiating angle at the time of processing a section can be arbitrarily set.
(24) In the sample fabricating apparatus in each of (21) and (22), the ion beam optical system controller controls the deflector on the basis of angle information that a set-section depression angle is projected to a plane including, as a normal line, the optical axis of the ion beam in correspondence with a set-section depression angle of a set section, and the specimen-stage position controller controls turning in the specimen stage plane of the specimen stage. Thus, a section at an arbitrary depression angle can be easily formed in an arbitrary processing position by turning a sample.
(25) In the sample fabricating apparatus in any of (21) to (24), angle information that a set-section depression angle of a set section is projected to a plane including, as a normal line, the optical axis of the ion beam is displayed on a display for displaying secondary particle information detected by the secondary particle detector and is set. With the configuration, the operator can visually make processing setting corresponding to a requested FIB irradiating angle.
(26) In the sample fabricating apparatus in each of (21) and (22), in correspondence with parameters of coordinates of a requested-section edge, a requested-section normal line direction, and a size, parameters equivalent to the parameters, or a combination of those parameters, the ion beam optical system controller controls the ion beam deflector, and the specimen-stage position controller controls turn in the specimen stage plane of the specimen stage. With the configuration, processing setting corresponding to section forming parameters desired by the operator can be automated.
(27) In the sample fabricating apparatus in any of (21) to (26), an input apparatus for setting a requested-section depression angle of a requested section or a parameter equivalent to the requested-section depression angle is provided. With the configuration, the operator can easily set the depression angle of the requested section.
(28) A sample fabricating method for irradiating a sample with an ion beam from an oblique direction to prepare a section by sputtering, including a step of setting a depression angle of a section requested to be observed in a sample, a step of determining a scanning-area edge of an ion beam in corresponding to the depression angle and setting a scanning area, and a step of processing the scanning area with the ion beam. Only by deflecting the ion beam, a section at an arbitrary tilt angle in a certain range can be formed.
(29) In the sample fabricating method of (28), by preparing a sample from a step of obtaining a turn angle of the requested section and a step of determining a turn angle of the sample in correspondence with the depression angle and the turn angle of the requested section, and setting turn in the specimen stage plane of the specimen stage, a section at an arbitrary tilt angle in a certain range in the requested section position can be formed.
(30) In a sample fabricating apparatus for forming a sample section in a sample held on a specimen stage by processing with a charged particle beam by using a charged particle beam optical system for condensing, scanning and deflecting a charged particle beam emitted from a charged particle source, an angle formed between the optical axis of the charged particle beam emitted from the charged particle beam optical system and a surface of the specimen stage is fixed, and formation of a sample section is controlled by turning of the specimen stage in the specimen stage plane.
(31) In a sample fabricating apparatus for forming a sample section in a sample held on a specimen stage by processing with a charged particle beam by using a charged particle beam optical system for condensing, scanning and deflecting a charged particle beam emitted from a charged particle source, an angle formed between the optical axis of the charged particle beam emitted from the charged particle beam optical system and a surface of the sample is fixed, and the scanning and deflection of the charged particle beam optical system is controlled in correspondence with an angle formed between a direction of a normal line of a section which is set for forming a sample section requested to be observed in the sample and the surface of the sample.